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Experts cast doubt on breast screening program

Julia Medew

AUSTRALIA'S breast screening program should be reassessed to make sure it is not causing more harm than good, leading epidemiologists say.

The deputy director of the Women's Health Research Program at Monash University, Robin Bell, said it could be argued that women should no longer be routinely invited to have mammograms in Australia's breast cancer screening program because of the significant risks of ''overdiagnosis''.

On Tuesday, an independent panel of experts in Britain said for every life saved by its breast screening program, another three women would be overdiagnosed and treated unnecessarily for cancer that would never have caused them harm.

This meant the program was preventing about 1300 breast cancer deaths every year while causing 4000 women to be overdiagnosed.

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The experts said that while the benefits of the program still outweighed the harms, in their view women should be given detailed information about the risk of overdiagnosis to make a more informed decision about screening. They also called for a reassessment of the cost-effectiveness of the screening program.

In response to the British findings, Professor Bell said Australia needed to rethink its approach to breast screening because the balance of harm and benefit had shifted considerably since the BreastScreen program began in the 1990s.

While the British panel used data from the 1970s and '80s to estimate a 19 per cent rate of overdiagnosis through breast screening, Professor Bell said more recent Australian research suggested 30 to 40 per cent of cancers detected in the BreastScreen program were overdiagnosed.

This meant the ratio of lives saved to overdiagnoses could be one to six in Australia, as opposed to the British estimate of one to three.

Given that a screening program has to produce more benefits than harms to be viable, she said it could be argued Australian women in their 50s and 60s should no longer be invited to attend screening because the invitation implied the benefits outweighed the risks.

The government could still provide free access to mammograms for women who wanted them, she said, particularly those with a strong family history of breast cancer.

''Given what we know, that this is not a clear-cut scenario where there are only benefits, I think you could make an argument for making screening available to people, but not necessarily continuing the invitation to screen,'' she said.

If the program continued to invite women, Professor Bell said they must be given easy to understand information about the pros and cons of screening so they could provide informed consent. ''Obviously, with any medical procedure, you want to make sure people are making an informed choice but I think the onus of responsibility is even greater when the invitation comes from outside,'' she said.

''If we're going to continue to invite women for screening we have to be really careful about how we present information to them so they can make an informed choice.''

Another epidemiologist and professor of public health at Sydney University, Alexandra Barratt, said while estimates about the benefits and harms of screening remained contentious, with arguments raging about methodology, Australian women were not being given enough information to provide informed consent for breast screening.

''As far as I'm aware, neither the invitation letter nor the commonly used brochures explain overdiagnosis,'' she said. ''They certainly don't do a good job of explaining in lay terms what it means to people and they don't give any estimate of how likely it is to occur.''

Professor Barratt said given the estimated pros and cons of breast screening now demanded a value judgment about what risk was preferable - the risk of late diagnosis and death or overdiagnosis - the government should not be simply encouraging women to get screened. She said trials of decision-making aids for screening showed women weighed up the benefits and risks differently.

''Some women say, 'When you put it like that, I still want to be screened' but other women look at the exact same data and say, 'No, I don't want to take that risk, I just want to live my life without getting into the medical system unless it's absolutely necessary and therefore I don't want to be screened,' '' she said.

''So rather than having a mindset of encouraging all women to be screened, I think we should make it very clear it is reasonable to decide either way and that you're not being irresponsible to look at the information and decide actually no, I don't want to do that.'' Professor Paul Glasziou, a GP and expert in evidence-based medicine, said he thought it was time for Australia to assemble a ''citizens jury'' of women to assess all the evidence themselves and make a decision about how the BreastScreen program should proceed and what information should be given to women about it.

''You can't leave that to the BreastScreen units because they have a conflict. Their key performance indicators are to get people in. They are good people but there is an unconscious bias there,'' he said.

John Boyages, director and professor of breast oncology at Macquarie University Cancer Institute, said he was very sceptical about the estimated rates of overdiagnosis and believed ''over-treatment'' was always better than ''under-treatment''.

While the British panel said breast cancer screening reduced a woman's chance of dying of breast cancer by 20 per cent, Professor Boyages said he believed the figure in Australia was about 25 per cent.

He said while it was time to review the information given to women, it was important not to scare people.

''My concern is that you're going to scare people and send out the wrong message,'' he said.

''It's important to emphasise that breast screening saves lives, that's what this [British] report has shown.''

A spokesman for Health Minister Tanya Plibersek said the government's Intergovernmental Standing Committee on Screening was monitoring emerging evidence about the harms and benefits of breast screening and that Cancer Australia was about to start reviewing the information given to women before they start screening.

''This work will involve consultation with BreastScreen Australia's program managers and consumers; and update the BreastScreen Australia National Information Statements. These statements promote national consistency in the public information and information to consumers provided by states and territories,'' the spokesman said.

5 comments

You mean the whitecoats may get it spectacularly wrong, not once in a while but on a regular basis! Over-diagnosis is a terrible consequence in light of the fact that out of 1300 women 'saved' 4000 were frightened enormously by a false positive. Imagine sitting there in front of your trusted health professional and being tpld, "sorry, you have cancer." Going through the treatment for cancer that is not even there. This is APPALLING.What about the amount of men who are told about their prostate cancer THAT ISN'T EVEN THERE?

Commenter

Don Juan Quixote

Date and time

November 01, 2012, 10:31AM

There's a difference between false positive and overdiagnosis. One is a positive result where in fact no cancer exists the other is a positive cancer result that is diagnosed correctly however may not require treatement. This is an extremely complex issue however critisising the 'white coats' and shouting APPALLING contributes nothing of worth to the debate. Perhaps you could tell us how you'd structure a population based screening program for these cancers?

Commenter

Massoir

Location

Perth

Date and time

November 01, 2012, 2:46PM

There is a difference between OVER-diagnosis and MIS-diagnosis. The article is referring to overdiagnosis, whereby women are screened, and subsequently treated for cancers which ARE present, but would have never presented clinically or caused them death or disability (the same thing is also fairly common in prostate cancer), and they are therefore caused more harm than benefit by having to go through unnecessary surgery, chemo/radiotherapy, not to mention the psychological stress caused by a cancer diagnosis. However, it is a tricky area because doctors are not be able to look at a cancer which has been detected through screening and predict either way whether it would cause death or not, so it's a bit of a catch-22. Misdiagnosis would be telling them they have cancer when in fact they do not.

Commenter

Nan

Date and time

November 01, 2012, 3:08PM

I am mother of 3 adult children - one diagnosed with breast cancer aged 30, another with prostate cancer aged 39. Had it not been for screening they would both be dead by now.

Commenter

juma

Date and time

November 01, 2012, 12:38PM

I've known about this for more than a decade, women should be very careful accepting information from our screening authorities. Fortunately, you can find real information on breast screening at the Nordic Cochrane Institute website, "The risks and benefits of mammograms" looks at ALL of the evidence and this group are independent medical researchers, so no bias in favour of screening. The NCI concluded a decade ago that breast screening is of little benefit, but leads to significant over-diagnosis. I made an informed decision to decline screening when I turned 50.AND, be careful with our pap testing program, it belongs in the Ark. Take a look at Finland's 6-7 pap test program, 5 yearly from 30 to 60, far less risk from false positives and over-treatment (the benefits of 2 and 5 yearly pap testing are the same, but 2 yearly testing creates FAR more false positives) or even better, the Dutch who have kept up with the evidence, their new program is 5 hrHPV primary triage tests (or you can self test with the Delphi Screener) at ages 30,35,40,50 and 60 and ONLY the roughly 5% who are HPV positive and at risk will be offered a 5 yearly pap test. Most women are HPV negative and not currently at risk...they will be offered the remaining 4 HPV primary tests. Our program seriously over-screens which means huge over-treatment and excess biopsies rates for NO additional benefit. Our programs need an INDEPENDENT review and need to be finally focused on what's best "for women" with some respect for informed consent. We also need to stop target payments to GPs for pap testing.HPV Today, Edition 24, sets out the new Dutch program and head over to the NCI site and read their brochure on breast screening. REAL information!